Question

What should be the indication on the magnetic compass as you roll into a standard rate turn to the right from a westerly heading in the Northern Hemisphere?

a) The compass will initially show a turn in the opposite direction, then turn to a northerly indication but lagging behind the actual heading of the aircraft
b) The compass will remain on a westerly heading for a short time, then gradually catch up to the actual heading of the aircraft.
c) The compass will indicate the approximate correct magnetic heading if the roll into the turn is smooth.

Answer 1

During a standard rate turn to the right from a westerly heading in the Northern Hemisphere, a magnetic compass will initially display a false turn indication due to inertia and then lag behind the actual turn heading.

Step-by-step explanation:

When you roll into a standard rate turn to the right from a westerly heading in the Northern Hemisphere, the magnetic compass will initially show a turn in the opposite direction due to the inertia of the compass needle. Shortly after, it will indicate a northerly turn but lag behind the actual heading of the aircraft. This is known as compass lag or northerly turning error, which occurs because the Earth's magnetic field lines are not parallel to the surface but angle down into the Earth. As a result, the horizontal component of the Earth's magnetic field, which the compass aligns with, changes with latitude and movement.